Electrode for search-lights.



H. VIERTEL. ELECTRODE FOR SEARCH LIGHTS. APPLIOATION FILED OUT. 25,1907.

v Patented. Apr. 6, 1909.

electrodes are convergent, and the cross-secportant object is animproved arrangement UNIT D s'rA rEs PATENT OFFICE.

HERMANN VIERTEL, OF OHARLOTTENBURG, GERMANY, ASSIGNOR TO GEBR. SIEMENS &

00., OF LICHTENBERG, NEAR BERLIN, GERMANY, 'A COPARTNERSHIP.

ELECTRODE FOR SE ARCH-LIGHTS.

To all whom itmay concern:

Be it known that I, HERMANN VIERTEL, a subject of the German Emperor,and resident at Knesebeckstrasse 32, (.harlottenburg, near Berlin,Germany, have invented new and useful Improvements in Electrodes forSearch-Lights, of which the folio-4. ingis a specification. t Thepresent invention relates to searchlights, projectors and the like, andan imof the electrodes in the same.

In accordance with the present invention the electrodes of arc-lamps forsearch-lights are arranged in such a manner that the tion of thepositive electrode is so proportioned that a burning surface. is formedof approximately oval or rectangular shape which is as closely aspossible adapted to the size and shape of the illuminating spot in theselected combination of electrodes. In this arrangement a burnin surfaceis formed which is almost perfect y fiat, and neither a disturbing edgeof a crater is formed, nor is the burning surface hollowed out in thedirection of the plane which passes through the axes of the two carbonswhich defects arise when positive carbons of circular cross-sectionhaving a more or less inclined position with regard to the negativecarbon are employed. Consequentl a much more favorable distribution ofight and much more perfect utilization of the light is obtained.

In order that the carbons may burn away uniformly and quietly and inorder that the illuminating spot may have an invariable position on theositive electrode, it is preferable to make t e negative electrode ofsubstantially smaller cross-sectional area than the positive electrode.It is best when the negative electrode is surrounded near the arc b atube of carbon or other suitable electrica ly conducting material, andwhen it can be displaced in this tube. I

The shape of the cross-section of the positive electrode is partiallydependent on the amount of the inclination of the two electrodes to oneanother. Generally speaking the shape of the positive electrodes will bea proximately oval or rectangular, as the il uminatin spot approachesthis shape when the e ectrodes are arranged in accord? ance with thepresent invention, and the Specification of'Letters Patent.

' Application filed October 25,

Patented Aprilfl, 1909,

1907. Serial No. 399,082.

burning surface of the electrode has to corres end with the illuminatingspot.

he most favorable arrangement of the electrodes is such that thepositive electrode having an oval cross-section is arranged in the axisof the search-light, whereas the negative electrode forms an angle ofmore than 90 with the positiveythis angle is determined by trial and isfound when the burning surface on the positive electrode approximatelyforms a plane at right-angles to the axis of the search-light. In thisarrangement the cross-sectionof the positive electrode mustapproximately correspond directly to the shape of'the illuminating spot.o i

In order to avoid changes of osition of the illuminating spot on the caron, which is of particular importance in this arrangement, because everychange of position may mean a loss of light and a non-unifornrutihzationof the carbons, it is preferable to assure the steadiness of the arc andthe uniformity of the position, shape and sizeof the illuminating spotby a blast-magnet. For

this-it is sufficient to provide an ,iron ring,

which is magnetized by the current, encircling the are or the points ofthe carbons.

In order that the invention may be clearly 1 understood reference ismade to the accompanying drawing in which a search-light is representedinsectional elevation, the carbons being arranged in accordance with theinvention.

In the drawing 0. indicates the positive carbon which for example mayhave an oval -or rectangular cross-section, as is represented b thehatched sections in the drawing; 1; in-

dicates the ne ative carbon arranged mclined at an ang e to the positivecarbon and formed as a thinner rod whleh can be displaced in an axialdirection in a casing c of conducting material. Both carbons are carriedb holders which are justable 0th by hand as we as by a mechanical orelectrical device. The

positive lpreferably adcarbon is situated in the axis of the opticalsystem.

(i is a universally adjustable iron ring I which acts as a blast-magnet,and 1s preferably siipported on the negative carbon holder. y means ofthis ring the arc can be adjusted in position. This ring is referablyopen above the arc, on account 0 the heat which would otherwise melt itat this point.

What I claim as my invention anddesire to secure by Letters Patent is:-

1. In asearch-light, the combination of a carbon-holder, a positiveelectrode having a cross-section with a larger and smaller axis carriedby said holder, another carbonholder, and a negative electrode carriedby the latter and directed from below toward "and at an oblique angle tothe positive electrode, said larger axis of the cross-section of thepositive electrode being situated in the plane of the two electrodes,for the purpose of adapting the cross-section of the positive electrodeto the shape of the illuminating surface of the crater and of avoidingdisturbing edges of the crater.

2. In a search-light, the combination of a carbon-holder, a positiveelectrode having an oval cross-section carried by said holder,

: another carbon-holder, and a negative'electrode carried by the latterand directed from {situated in the plane of the below toward and at anoblique angle to the gplane of the two electrodes, a blast-m holder, anda negative electrode carried by the latter and directedfrom below towardand atan oblique angle to the positive electrode, said larger axis ofthe cross section of the positive electrode being situatedin the at.-ada ted to regulate an are between the e ec- -tro es, and means'foradjusting universally the position of said magnet, for the pu ose ofassuring the required uniformit to the 7 position, shapeand size of theilluminating! spot on the positive electrode; 1 v s f 4. In asearch-light, the combination of a carbon-holderfa positive electrodehaving a v cross-section with a larger and smaller carried by saidholder, another carbon-holder, and a negative electrode carried by thelatter and directed from below toward and at an oblique angle to thepositive electrode, said larger axis of the cross-section ofthe positiveelectrode being situated in the planeof the two electrodes, and an ironring encircling j the negative electrode, and means for uni-.' 5

versally adjusting the position of said ring,

as and for the purpose specified. M In testimony whereof I have signedmyname to this specification in the presence of Y two witnesses.

. HERMANN VIERTEL-fl Witnesses: p

WOLDEMAB. HAUP'r.

l IENRYLHASPER."

